1. Field of the Invention
This invention relates in general to power supplies and more specifically to techniques for load step transient suppression for a power supply.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, and/or communicated, and how quickly and efficiently the information may be processed, stored, and/or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and/or communicate information and may include one or more computer systems, data storage systems, and/or networking systems.
Information handling systems typically include electronic components requiring regulated power for operation. Power supplies for these components may include DC switching regulators for providing power at regulated voltages.
One potential problem for power supplies of information handling systems is that they can be exposed to load step transients, where load demand of the power supply transitions very rapidly from a maximum power demand to low or no power demand. When such a transition occurs, the voltage level of a switching regulator output can rise rapidly due to the energy stored in an inductor of an LC (inductor-capacitor) filter circuit of the switching regulator. If the output voltage level rises too high, it may exceed the voltage tolerances of the components being powered, thereby tripping over voltage protection circuits or in some cases, causing the loss of data or damage to the information handling system.
Techniques for handling load step transients have included operating a switching regulator at a higher switching frequency and increasing the amount of bulk filter capacitance. However, operating a switching regulator at a higher frequency can reduce the power efficiency of the regulator. Increasing the bulk filter capacitance increases the expense and the required board space of a regulator.
What is needed is an improved system for minimizing the effect of a load step transient on a switching regulator.
It has been discovered that providing a switching regulator with a suppression circuit can advantageously minimize the effect of a load step transient on the switching regulator.
In one aspect of the invention, a switching regulator includes a inductive element having a first end which receives current from a power source. The inductive element has a second end coupled to an output of the regulator. The switching regulator also includes a first switch controlling the supply of current to the inductive element from the power source, a suppressor element, and a first potential at a voltage level. The switching regulator also includes a second switch and a control circuit. The control circuit controls the second switch. In response to a determination of an over voltage condition, the control circuit controlling the second switch to couple the suppressor element to the inductive element for current to flow from the suppressor element to the inductive element whereby the first end of the inductive element is at a voltage level that is less than the voltage level of the first potential.
In another aspect, the present invention includes a method of operating a switching regulator including an inductive element having a first end which receives current from a power source as controlled by a first switch. The inductive element has a second end coupled to an output of the regulator. The method includes detecting an over voltage condition of the switching regulator and in response to the detection, controlling a second switch to enable current to flow through a current path from a first potential to the first end of the inductive element and including a suppressor element whereby the first end of the inductor is at a voltage level that is less than the voltage level of the first potential.
In another aspect of the invention, a direct current buck regulator includes an LC filter having an inductor and a capacitor and a first switch controlling the supply of current to the inductor from a power source. The first switch is coupled to a first end of the inductor. A second end of the inductor is coupled to the capacitor and to an output of the regulator. The regulator also includes a suppressor element, a first potential at a first voltage level, and a second switch. The regulator also includes a control circuit controlling the second switch. In response to a determination to a determination of an over voltage condition of the output, the control circuit controlling the second switch for current flow from the suppressor element to the inductor whereby the first end of the inductor is at a voltage level that is less than the voltage level of the first potential.